Influence of Soot Particles on the Gas-Phase Methane Conversion into Synthesis-Gas. The Role of H₂O and CO₂ Additives

Abstract

The influence of the formation of microheterogeneous soot particles on the gas-phase conversion of rich mixtures of methane with oxygen into synthesis gas in the temperature range from 1500 to 1800 K under the conditions of an adiabatic reactor was studied by kinetic modeling. The effect of CO2 and H2O additives on this process was studied. The appearance of soot particles is observed in rich mixtures, starting from the fuel excess factor ϕ = 3.33. At relatively low temperatures ~1500 K, a small amount of microheterogeneous soot particles is formed, which do not significantly affect the other components of the reacting system. A noticeable effect of soot particles at this temperature is observed at a higher value of ϕ = 8.0. This is most clearly manifested in the temperature profile of the process, in which, with the addition of water, two maxima are observed at times of the order of 0.01 and 0.1 s. In the case of CO2 additions, the second maximum on the temperature profile is almost not pronounced. A complex temperature profile leads to the appearance of the second maximum concentration of OH hydroxyl radicals at times of ~0.1 s. The addition of H2O and CO2 makes it possible to vary the H2/CO ratio in the synthesis gas over a wide range, which is necessary for the synthesis of various products. Since the added CO2 under these conditions is actually involved in the chemical process of obtaining synthesis gas, its partial recirculation from the conversion products makes it possible to reduce its emission during the production of synthesis gas.